Need help with X9 Rear Derailleur

My X9 RD gets stuck on my largest cog and it won't fall to the next cog when I shift down. I took the derailleur off my bike and it would get stuck in the same position which led me to think that the parallelogram pivots needed lubing, which I did and it helped a bit but it's still not coming off the top cog. It's as if the spring is not strong enough to pull it down even though the cable tension is completely off. When I'm in the middle of my cog set it has no problem shifting down and I can shift up from bottom to top without problems. It's only 2 months old but it seems to have started happening recently after a couple of very wet rides. Does anybody have thoughts on how I could resolve the problem without getting a new RD? I'm thinking of loosening the parallelogram pivots to see if there's grit stuck in them but I don't know how to do that? Any advise would be appreciated.

My X9 RD gets stuck on my largest cog and it won't fall to the next cog when I shift down. I took the derailleur off my bike and it would get stuck in the same position which led me to think that the parallelogram pivots needed lubing, which I did and it helped a bit but it's still not coming off the top cog. It's as if the spring is not strong enough to pull it down even though the cable tension is completely off. When I'm in the middle of my cog set it has no problem shifting down and I can shift up from bottom to top without problems. It's only 2 months old but it seems to have started happening recently after a couple of very wet rides. Does anybody have thoughts on how I could resolve the problem without getting a new RD? I'm thinking of loosening the parallelogram pivots to see if there's grit stuck in them but I don't know how to do that? Any advise would be appreciated.

i have the same problem with my XO, i couldn't figure it out so i ripped it off and decided to run chainless till i have money to do something about it

try backing off the b knuckle adjustment? basically move the upper jockey wheel away from the cassette a bit.

I also had my X9 get sticky after this weekend. Juiced 'er up with triflow and worked it back and forth.

go singlespeed?

try backing off the b knuckle adjustment? basically move the upper jockey wheel away from the cassette a bit.

I also had my X9 get sticky after this weekend. Juiced 'er up with triflow and worked it back and forth.

This tip was pure genius. I had played with the B-screw but never really understood how it affected shifting. Mine was basically completely unscrewed so that the jockey wheel was very close to the cassette. It's now almost completely the other way and this solved it (along with some extra lube for good measure). Thanks.

what size cassette do you have on your bike? You can't run some derailleurs with a 11-34 cassette. you might need a 11-32 instead if the tension screw adjustment doesn't fix your problem. different manufacturers have a different pivot location for the derailleur depending on the design.

Now if the derailleur stays stuck even off the bike then that means the linkages are bent and it's getting caught on the B-knuckle of the derraileur. you'll have to replace the derailleur

There should be 1 1/2 links between where the chain comes off the largest cog and enters the top guide pulley.

This tip was pure genius. I had played with the B-screw but never really understood how it affected shifting. Mine was basically completely unscrewed so that the jockey wheel was very close to the cassette. It's now almost completely the other way and this solved it (along with some extra lube for good measure). Thanks.

I wouldn't back it the total other way if you don't need it. you want it pretty close as long as you're not binding.

Thanks for all the advise. I'll check out my cassette size and the number of links between the largest cog and the upper pulley. The b-screw is not completely in. It's maybe 85[HTML_REMOVED]#37; in. The angle of my chain as it comes off the cassette has definitely changed. Before I played with it, it was running in a very horizontal manner but now it's much more vertical. Is there a downside to this?

Putting a little blue loctite or plumbers teflon tape on the B-screw will prevent it from moving again.

I had the same problem once with my XO and adjusting the B-screw fixed it and to prevent it from happening again I put loctite on the screw first. 5 months later and no issues so far.